.toUpperCase() converts 'ß' to deprecated 'SS'

[t-m-z]

According to wikipedia

Dart .UpperCase() converts ß to SS while the capital ⟨ẞ⟩ was encoded by Unicode in 2008 at (U+1E9E ẞ LATIN CAPITAL LETTER SHARP S).

In 2017, the Council for German Orthography officially adopted a capital, ⟨ẞ⟩, as an acceptable variant in German orthography, ending a long orthographic debate.[4] Since 2024 the capital ⟨ẞ⟩ (ligature) has been preferred over ⟨SS⟩ (two letters).[5]

Hence I think the conversion from 'ß' to 'SS' is deprecated and should be changed to 'ẞ'

[lrhn]

The most recent version of Unicode still has the two-letter uppercasing for U+00DF, so I expect this to change when the next Unicode version is released, and the ICU library is updated.

See: https://www.unicode.org/Public/16.0.0/ucd/SpecialCasing.txt

The Unicode version was released about a month after the official change, so the change probably didn't get in before the feature freeze for that release.

Or maybe it won't change. Unicode has some stability guarantees, one of which is:

If two characters do not form a case pair in a version of Unicode, they will never become a case pair in any subsequent version of Unicode.

That would mean that the lower- and upper-case sharp S can't become the canonical other case of each other. Or maybe it only means that the mapping would have to stay in the SpecialCasing file. Not sure how they're going to handle this, I guess we'll have to wait and see.

(Edited: Had written 00D5 instead of 00DF.)

[t-m-z]

Thank you for your quick answer.

Just for clarification: You mentioned U+00D5. This is Latin Capital Letter O with Tilde, I think.
'"ß" Latin Small Letter Sharp s is Unicode Character “ß” (U+00DF).

Regarding your quote about case pairs, I think unicode is a kind of faulty.

According to https://www.[unicode.org/Public/UNIDATA/UnicodeData.txt](https://www.unicode.org/Public/UNIDATA/UnicodeData.txt) U+1E9E Latin Capital Letter Sharp s points to U+00DF whereas U+00DF has no Uppercase mapping which is not in line with the german language authority as described in the wikipedia article.

[lrhn]

Ack, the 00D5 was a typo, will fix.

Unicode does have an upper-case for ß, but since it's not a single letter, it's in the SpecialCasing file that I linked to.
The upper-case transform of "ß" is "SS".
That used to be a valid transformation.

We'll have to see what the Unicode consortium does with the new recommendation.
By their documented stability rules, it seems they can't just change that to "ẞ".

[t-m-z]

Ack... ... and wait... However keeping stability and neglecting language authorities would be poor.

…

-----Original Message----- From: "Lasse R.H. Nielsen" ***@***.***> To: dart-lang/sdk ***@***.***> Cc: Thomas ***@***.***>, Author ***@***.***> Sent: So., 16 Feb. 2025 9:29 Subject: Re: [dart-lang/sdk] .toUpperCase() converts 'ß' to deprecated 'SS' (Issue #60141) lrhn left a comment (dart-lang/sdk#60141) Ack, the 00D5 was a typo, will fix. Unicode does have an upper-case for ß, but since it's not a single letter, it's in the SpecialCasing file that I linked to. The upper-case transform of "ß" is "SS". That used to be a valid transformation. We'll have to see what the Unicode consortium does with the new recommendation. By their documented stability rules, it seems they can't just change that to "ẞ".

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